Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Likely
- Size
- 2–3
Recent avalanches: There was a widespread avalanche cycle from January 14th to 16th in the Summit Lake zone. Since then, there have been tons of collapses reported from the Summit Lake area, but no new avalanches.
The intensity of the current storm system is expected to ratchet up today, with 4 to 6" of new snow expected in Summit Lake. Stronger southeast winds will accompany the heavier snowfall, averaging 20 to 30 mph with gusts up to 45 mph. This gradual accumulation of new snow and wind is likely to be enough to make our weak layer, which is buried 1 to 3' deep, more sensitive to human-triggered avalanches and could cause some natural avalanches in specific areas that receive more wind loading.
While the likelihood of triggering an avalanche today is on the rise, the advice for how to deal with the problem stays the same. You can use conservative terrain selection to control your risk exposure by sticking to simple, low-angle terrain and avoiding the runout zones of overhead avalanche paths. Remotely triggered avalanches have been especially common on this weak layer, which means you could trigger an avalanche from low-angle terrain onto connected steeper terrain.
(1/20/2026) Snowpack structure at treeline in Summit Lake before the current storm started. Photo: John Sykes